Countries around the world are trying to solve the problem of EV charging by accelerating the construction of charging stations, with EV makers striving to advance battery technologies. However, extreme cold can cause trouble to EV owners as freezing conditions affect the performance of Li-ion batteries—a crucial component powering their vehicles. The historic winter storm blasting the US recently has prompted Tesla owners to complain that the blizzard has caused a range dip and that they cannot charge their vehicles.
A Tesla owner, for example, recently told the media that his EV battery was 40% charged at 19°F (around 7°C) outside. After charging for 2 hours, the battery level did not change much. As the temperature got lower, the charge became inefficient and fully stopped in the end. Because the car could only go for 19 miles with the remaining charge, he was forced to cancel his holiday trip.
A Taiwanese tech worker in New York also grumbled about the charging problem on social media when the city was hit hard by the winter storm, saying, “Winter is really a big challenge to EVs. At sub-zero temperatures, the Model Y keeps telling me to warm the battery before going on for a DC charge. This warm-up process is required only for AC charging in average weather. The charging speed thus slowed down dramatically. If the car stays at sentry mode when parked, it can lose nearly 10% of its range overnight.”
Li-ion batteries are prone to damage when charged below 0°C as lithium plating occurs at the freezing point. To avoid this chemical reaction in cold weather, EV systems will spend some time on heating up the battery to a certain temperature before actually initiating a charge, consequently increasing the charging time. Moreover, the battery range of EVs are lower under freezing conditions, as EV makers like Tesla restrict the capacity of batteries when their temperature is excessively low with an effort to protect them. The retained capacity can be accessed when the battery temperature returns to a normal level.
An EV's range can largely slump in cold weather. According to a range test done in winter environments by the American Automobile Association, range fell by 41% at 20°F (−6.7°C) on average among the five EV models (including the Model 3) it tested. During the test, the Model 3 was stopped to let the cabin cool down. When the car was turned on again, the vehicle must use part of its battery capacity to heat the cabin, resulting in a range reduction. However, the Model 3 was not equipped with a heat pump system when the test was conducted. Therefore, later models with heat pumps will have better heating efficiency than their predecessors adopting resistance heating.
Batteries Have Limits
A Norwegian Automobile Federation study showed that EVs in Norway—where half of all new cars are powered by electricity—lost about 20% of their driving range in winter and took more time to charge in extreme cold. To maximize an EVs’ driving range in winter, experts and carmakers have offered some tips for EV owners, such as keeping the vehicle plugged in when not driving it, keeping the car warm, and even setting the time to pre-warm and pre-charge the vehicle before heading out.
Still, batteries have limits. As Anna Stefanopoulou, director of the University of Michigan’s Energy Institute, said, “Batteries are like humans. They prefer the same sort of temperature range that people do. Anything below 40°F (4°C) or above 115°F (46°C) and they’re not going to deliver their peak performance.”
EVs have no problem with charging in warm weather and can survive the cold of winter if the driver follows corresponding guidelines. Although driving a Tesla is a cool thing, gasoline cars might be more suitable for those who want to save the trouble of complex technical settings as extreme cold may be more common in the future.
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